Ballard Locks Stoney Gate Valve Replacement

The Stoney Gate Valve Replacement project for the U.S. Army Corps of Engineers (USACE) replaced the original 100-year-old filling culvert gates at the large lock chambers of the Hiram M. Chittenden Locks, also known as the Ballard Locks. IMCO also replaced the large lock center gate bushings and gudgeon pin—critical components that support the gates’ weight and allow them to rotate open and closed. 

The existing stoney gate valves were more than 105 years old and original to the structure. The project team completed demolition, removal, and replacement of the valves and installed new hydraulic power systems and operating machinery. The stoney gate valve system consisted of six valves that controlled the filling and emptying of the large lock chambers on Lake Washington. The valves were housed in culverts measuring 14 by 8.5 feet and were only accessible when the chambers were dewatered by the government. This work was completed across three separate dewatering events. 

As the busiest lock and dam facility in the United States by vessel count, the Ballard Locks required careful coordination to minimize impacts. Through collaboration with USACE, subcontractors, and suppliers, IMCO expedited material delivery, resequenced the project schedule, and successfully eliminated the need for a fourth lock closure. Avoiding the final dewatering event reduced impacts on the surrounding community, allowing boaters and local businesses to continue moving freely between Puget Sound, Lake Union, and Lake Washington.